Micro/nano technology devices are known in the art as devices with components on the scale of 1 μm to 100 s of μm that cooperate to perform various desired functions. In particular, microfluidic devices are micro/nano technology devices that perform fluid handling functions, which, for example, cooperate to carry out a chemical or biochemical reaction or analysis.
Most microfluidic devices in the prior art are based on fluid flowing through microscale passages and chambers, either continuously or in relatively large aliquots. Fluid flow is usually initiated and controlled by electro-osmotic and electrophoretic forces. See, e.g., U.S. Pat. No. 5,632,876, issued Apr. 27, 1997 and titled “Apparatus and Methods for Controlling Fluid Flow in Microchannels;” U.S. Pat. No. 5,992,820, issued Nov. 30, 1999 and titled “Flow Control in Microfluidics Devices by Controlled Bubble Formation;” U.S. Pat. No. 5,637,469, issued Jun. 10, 1997 and titled “Methods and Apparatus for the Detection of an Analyte Utilizing Mesoscale Flow Systems;” U.S. Pat. No. 5,800,690, issued Sep. 1, 1998 and titled “Variable Control of Electroosmotic and/or Electrophoretic Forces Within a Fluid-Containing Structure Via Electrical Forces;” and U.S. Pat. No. 6,001,231, issued Dec. 14, 1999 and titled “Methods and Systems for Monitoring and Controlling Fluid Flow Rates in Microfluidic Systems.”
These devices are relatively disadvantageous because, inter alia, they require larger volumes of reactants by virtue of their flow-based design, and fluid control by electro-osmotic and electrophoretic forces typically requires relatively large voltages, which may be dangerous and are difficult to generate in small portable control devices. Control devices for microfluidic devices based on such technologies are larger, at least desktop in size.
More advantageous technologies for microfluidic devices has been developed by one or more of the inventors or the present application and others. This advantageous technology manipulates very small aliquots of fluids (known herein as “micro-droplets”) in microscale passages by relying largely on pressure and other non-electric forces. These devices are advantageous in that smaller volumes of reagents are required, and in that non-electric forces can be generated by smaller voltages, of the order of magnitude output by standard microelectronic components. See, i.e., U.S. Pat. No. 6,057,149, issued May 2, 2000 and titled “Microscale Devices And Reactions In Microscale Devices;” U.S. Pat. No. 6,048,734, issued Apr. 11, 2000 and titled “Thermal Microvalves in a Fluid Flow Method” and U.S. Pat. No. 6,130,098, issued Oct. 10, 2000.
However, to the knowledge of the inventors, no well-structured control systems have been provided for such micro-droplet-based microfluidic devices that exploits the essential advantages of such devices.
Citation or identification of any reference in this Section or any section of this application shall not be construed that such reference is available as prior art to the present invention.